Magnetically modified hydroxyapatite nanoparticles for the removal of uranium (VI): Preparation, characterization and adsorption optimization.

Recently, magnetically modified nanomaterials have gained a great interest in the field of wastewater remediation. In this regard, the present work introduces a facile microwave-assisted pathway for the preparation of magnetically modified hydroxyapatite nanoparticles (MNHA) and evaluates its adsorption capability towards the removal of uranium (VI) ions from wastewaters. The prepared magnetic nanocomposite went through a full characterization procedure using different techniques, such as transmission electron microscope (TEM), X-ray diffraction (XRD), FT-IR, Brunauer-Emmett-Teller (BET) surface area measurements and magnetization curve. Involvement of the prepared MNHA in the remediation of wastewater containing U(VI) ions was investigated and the factors that influence the adsorption capacity were considered and optimized. The adsorption's optimum pH was found to be 5.0 and equilibrium was attended after 120 min. A maximum adsorption capacity of 310 mg/g was achieved after 120 min at 25 °C. The experimental data were well explained by Langmuir adsorption isotherm model. Kinetically, the adsorption process follows the pseudo-second order model. Thermodynamically, it is endothermic, irreversible and spontaneous adsorption process. Removal of U(VI) ions was found to take place via complex formation between the phosphate groups on the adsorbent and uranyl ions. The recovery of U(VI) ions from MNHA beads and the reusability of the spent beads were also explored. It was concluded that the prepared MNHA nanocomposite is simple, fast, ecofriendly adsorbent for the removal of U(VI) ions from water with excellent adsorption capacity.